Acidification

PML

WHAT IS ALREADY HAPPENING

WHAT COULD HAPPEN

The ocean is becoming more acidic as increasing atmospheric carbon dioxide (CO2) is absorbed at the sea surface. Models and measurements suggest that surface pH has decreased by 0.1 pH unit since 1750.

The surface ocean has absorbed nearly half of the increased CO2 emissions due to burning of fossil fuels over the last 250 years, thus reducing the amount remaining in the atmosphere.

Continued acidification will reduce the ability of the ocean to take up CO2 from the atmosphere, which will have feedbacks to future climate change, further accelerating the accumulation of CO2 in the atmosphere.

Future increases in ocean acidity will have major negative impacts on some shell/skeleton-forming organisms within this century.

Nearly half of the CO2 derived from burning fossil fuel has already been absorbed by the surfaces of our seas and oceans and more will be absorbed in the future as we continue to increase our CO2 emissions to the atmosphere. The ocean uptake of CO2 is effectively buffering even more serious climate change than that predicted by clear evidence-based scientific consensus. Continued acidification will reduce the ability of the ocean to take up CO2 from the atmosphere, which will have feedbacks to future climate change, further accelerating the accumulation of CO2 in the atmosphere.

We have a high degree of confidence that reducing emissions is the only way of reducing ocean acidification.

Knowledge gaps

Many, and in all areas, as this field is very much still emerging, they are mentioned briefly in the text above and more specifically in Royal Society, 2005; JGR, 2005; Haugen et al., 2006; Kleypas et al., 2006; Blackford et al., 2007.

Commercial impacts

Potentially fisheries will be impacted through changes to marine productivity and biodiversity and shell fisheries through reduced physiological functioning such as growth rate, reproduction and survival/recruitment of larvae and juveniles.